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Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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1

Orina, Paul S., David M. Onyango, Henry Lungayia, Andrew Oduor, Anthony W. Sifuna, Petronila Otuya, Rosemary A. Owigar, Chrispin B. Kowenje, and Sheban M. Hinzano. "Water Quality of Selected Fishing Beaches of Lake Victoria Kenyan Gulf." Open Journal of Ecology 10, no. 01 (2020): 22–35. http://dx.doi.org/10.4236/oje.2020.101002.

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2

Jovanelly, Tamie J., Julie Johnson-Pynn, James Okot-Okumu, Richard Nyenje, and Emily Namaganda. "Pioneering water quality data on the Lake Victoria watershed: effects on human health." Journal of Water and Health 13, no. 3 (June 8, 2015): 920–30. http://dx.doi.org/10.2166/wh.2015.001.

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Four forest reserves within 50 km of Kampala in Uganda act as a critical buffer to the Lake Victoria watershed and habitat for local populations. Over a 9-month period we capture a pioneering water quality data set that illustrates ecosystem health through the implementation of a water quality index (WQI). The WQI was calculated using field and laboratory data that reflect measured physical and chemical parameters (pH, dissolved oxygen, biological oxygen on demand, nitrates, phosphates, fecal coliform, and temperature turbidity). Overall, the WQI for the four forest reserves reflect poor to medium water quality. Results compared with US Environmental Protection Agency and World Health Organization drinking water standards indicate varying levels of contamination at most sites and all designated drinking water sources, with signatures of elevated nitrates, phosphates, and/or fecal coliforms. As critical health problems are known to arise with elevated exposure to contaminants in drinking water, this data set can be used to communicate necessary improvements within the watershed.
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3

Faustine, Anthony, and Aloys N. Mvuma. "Ubiquitous Mobile Sensing for Water Quality Monitoring and Reporting within Lake Victoria Basin." Wireless Sensor Network 06, no. 12 (2014): 257–64. http://dx.doi.org/10.4236/wsn.2014.612025.

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4

Okullo, W., B. Hamre, Ø. Frette, J. J. Stamnes, K. Sørensen, T. Ssenyonga, J. Høkedal, K. Stamnes, and A. Steigen. "Validation of MERIS water quality products in Murchison Bay, Lake Victoria – Preliminary results." International Journal of Remote Sensing 32, no. 19 (July 12, 2011): 5541–63. http://dx.doi.org/10.1080/01431161.2010.506895.

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5

Opere, Wasonga Michael, Maingi John, and Omwoyo Ombori. "Occurrence of Enteric Viruses in Surface Water and the Relationship with Changes in Season and Physical Water Quality Dynamics." Advances in Virology 2020 (July 3, 2020): 1–11. http://dx.doi.org/10.1155/2020/9062041.

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Environmental water quality issues have dominated global discourse and studies over the past five decades. Significant parameters of environmental water quality include changes in biological and physical parameters. Some of the biological parameters of significance include occurrence of enteric viruses. Enteric viruses can affect both human and animal’s health by causing diseases such as gastrointestinal and respiratory infections. In this study, the relationship between the occurrence of enteric viruses with reference to adenoviruses and enteroviruses and the physical water quality characteristics was assessed from water samples collected from Lake Victoria (LV) in Kenya. In order to understand the dynamics of season driven enteric viruses’ contamination of the lake waters, we additionally analysed seasonal behavior of the lake’s catchment area in terms of rainfall effects. Physical quality parameters were measured on-site while viral analysis was carried out by molecular methods using the nested polymerase chain reaction (nPCR). From 216 samples that were analysed for viral contamination, enteric viral genomes were discovered in 18 (8.3%) of the samples. Out of half of the samples (108) collected during the rainy season, enteric viral genomes were detected in 9.26% (10) while 8 (7.41%) samples tested positive from the other half of the samples (108) collected during the dry season. There was, however, no significant correlation noted between the physical water quality characteristics and the enteric viruses’ occurrence. Neither wet season nor dry season was significantly associated with the prevalence of the viruses. In Lake Victoria waters, most of the samples had an average of physical water quality parameters that were within the range accepted by the World Health Organization (WHO) for surface waters with exemption of turbidity which was above the recommended 5 NTU as recorded from some sampling sites. Continuous and long-term surveillance of the lake water to accurately monitor the contaminants and possible correlation between chemical, physical, and biological characteristics is recommended. This would be important in continuous understanding of the hydrological characteristics changes of the lake for proper management of its quality with reference to the WHO standards. A multiple varied-sampling approach in different geographical regions during different seasons is recommended to establish the geographical distribution and relatedness to seasonal distribution patterns of the viruses. The data generated from this study will be useful in providing a basis for assessment of seasonally driven fecal pollution load of the lake and enteric virus contamination for proper management of the sanitary situation around the lake.
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6

Juma, Dauglas Wafula, Hongtao Wang, and Fengting Li. "Impacts of population growth and economic development on water quality of a lake: case study of Lake Victoria Kenya water." Environmental Science and Pollution Research 21, no. 8 (January 18, 2014): 5737–46. http://dx.doi.org/10.1007/s11356-014-2524-5.

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7

GAVRILESCU, Elena, and Gilda Diana BUZATU. "Water Quality of Some Lakes in Dolj County." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 70, no. 2 (November 25, 2013): 370–76. http://dx.doi.org/10.15835/buasvmcn-agr:9679.

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In Dolj County there are a number of lakes that are particularly important, because they have a large quantity of water, some of them originating from hydrotechnical accumulations, and other from natural waters. In the present study, it was performed the monitoring of the water quality of the lakes in Dolj County, in the year of 2012, namely: Victoria - Geormane, Bistreţ and Caraula. The ecological conditions of the natural and artificial lakes was established based on the state of acidification, of the oxygen regime (dissolved oxygen, biochemical oxygen demand and chemical oxygen demand), the degree of eutrophication (biogenic substances, phytoplankton biomass and chlorophyll “a”) and also based on transparency. The water samples were taken from three points: tail, middle and upstream of the lake and were analyzed using high performance equipment, namely: pH-meter, spectrophotometer DR 2010, Sechi disc, BOD5 system. In terms of the degree of eutrophication, the water from the studied lakes belongs to the third category of water quality. Geormane is a natural lake which has a very good ecological status, except regarding the eutrophication, which is considerably visible. Bistret lake has a good environmental status and is visible eutrophic. Caraula lake’s water belongs to the third category of water quality, being heavily eutrophic.
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8

Simiyu, Benard Mucholwa, Harold Sabula Amukhuma, Lewis Sitoki, William Okello, and Rainer Kurmayer. "Interannual variability of water quality conditions in the Nyanza Gulf of Lake Victoria, Kenya." Journal of Great Lakes Research 48, no. 1 (February 2022): 97–109. http://dx.doi.org/10.1016/j.jglr.2021.10.017.

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9

Gidudu, A., R. Mugo, L. Letaru, J. Wanjohi, R. Nakibule, E. Adams, A. Flores, B. Page, and W. Okello. "Evaluation of satellite retrievals of water quality parameters for Lake Victoria in East Africa." African Journal of Aquatic Science 43, no. 2 (June 21, 2018): 141–51. http://dx.doi.org/10.2989/16085914.2018.1446899.

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10

Jones Muyodi, Fredrick. "Beach Community-Designed System To Ameliorate Water Quality Deterioration in Catchments of Lake Victoria." Open Environmental Engineering Journal 5, no. 1 (July 13, 2012): 84–95. http://dx.doi.org/10.2174/1874829501205010084.

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11

Nyawacha, S. O., V. Meta, and A. Osio. "SPATIAL TEMPORAL MAPPING OF SPREAD OF WATER HYACINTH IN WINUM GULF, LAKE VICTORIA." International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2021 (June 28, 2021): 341–46. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2021-341-2021.

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Abstract. Water hyacinth (Eichhornia crassipes) is an invasive hydro plant that invaded the waters of Lake Victoria and has since been spreading rapidly affecting the socio-economic livelihood of the community around the Lake. The weed's rapid spread is due to various anthropogenic activities in the surrounding environment among them being the eutrophication of the lake waters.This study aims at using remote sensing applications and presenting the results of the analysis of the water hyacinth Normalized Difference Vegetation Index (NDVI), water extent, and analysis of correlation with the water quality over time from Sentinel 2 satellite imagery in January 2017 to January of 2021. The analysis aims at understanding the vegetation growth coverage in the five years and sets the basis of monthly predictive modelling of the behavior of water hyacinth. Predictive modelling applies historical statistical data while trying to use trend analysis in predicting the future behavior of a phenomenon. This study also seeks to answer the research question of the role of suspended sediments and dissolved minerals in abating the spread of and growth of water hyacinth.
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12

Faustine, Anthony, Aloys N. Mvuma, Hector J. Mongi, Maria C. Gabriel, Albino J. Tenge, and Samuel B. Kucel. "Wireless Sensor Networks for Water Quality Monitoring and Control within Lake Victoria Basin: Prototype Development." Wireless Sensor Network 06, no. 12 (2014): 281–90. http://dx.doi.org/10.4236/wsn.2014.612027.

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13

Machiwa, Praxeda K. "Water quality management and sustainability: the experience of Lake Victoria Environmental Management Project (LVEMP)––Tanzania." Physics and Chemistry of the Earth, Parts A/B/C 28, no. 20-27 (January 2003): 1111–15. http://dx.doi.org/10.1016/j.pce.2003.08.032.

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14

Cózar, Andrés, Nadia Bergamino, Stefania Mazzuoli, Nicholas Azza, Luca Bracchini, Arduino M. Dattilo, and Steven A. Loiselle. "Relationships between wetland ecotones and inshore water quality in the Ugandan coast of Lake Victoria." Wetlands Ecology and Management 15, no. 6 (June 12, 2007): 499–507. http://dx.doi.org/10.1007/s11273-007-9046-6.

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15

Simonit, Silvio, and Charles Perrings. "Sustainability and the value of the ‘regulating’ services: Wetlands and water quality in Lake Victoria." Ecological Economics 70, no. 6 (April 2011): 1189–99. http://dx.doi.org/10.1016/j.ecolecon.2011.01.017.

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16

Makalila, Shadrack. "Community Initiatives in Water Quality Management in Simiyu Wetland in the Lake Victoria Basin, Tanzania." JOURNAL OF THE GEOGRAPHICAL ASSOCIATION OF TANZANIA 34 (July 10, 2021): 114–27. http://dx.doi.org/10.56279/jgat.v34i.87.

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17

Makaka, R. R., Shepherd Misi, Mhosisi Masocha, and Richard Kimwaga. "Spatial and Temporal Variation of Selected Water Quality Parameters in the Tanzanian Side of Lake Victoria." Tanzania Journal of Engineering and Technology 40, no. 2 (February 20, 2022): 1–23. http://dx.doi.org/10.52339/tjet.v40i2.729.

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Lake Victoria’s water quality is increasingly becoming under heavy pressure mainly due to land based activities and aerial inputs which are taking place within the basin. This study was carried out to assess the spatial, including vertical and temporal, variation of the water quality of Lake Victoria on the Tanzanian side. Historical water quality data for the period from 2000 to 2016 was collected. Temperature, pH, Dissolved Oxygen (DO) and Turbidity were selected for study since they are the mostly measured and monitored water quality parameters. Land use-land cover changes were analysed using ArcGIS. ILWIS 3.7 software was used to classify the land use and land cover for the years 2000, 2010 and 2014. MERIS was used to analyse the spatial variation. One-way ANOVA was employed to test the significant variation between different parameters. The results showed that, for the pelagic zone, the range of temperature, pH, DO, and turbidity were 22.8 oC-28.68 oC, 6.3-10.52, 3.42-10.21 mg/l, 1.0 NTU-15.8 NTU respectively. The corresponding values for the littoral zones were 22.3 oC-26.8 oC, 6.47-10.16, 3.99-8.6 mg/l, 1.3-347 NTU respectively. The ANOVA analysis results show that there was a significant variation of NO3(p<0.01). Temperature, pH and DO decreased with the lake depth to the bottom for both zones. For the littoral zone, a strong correlation was observed between temperature and depth, temperature and DO, and between temperature and pH with R2=0.6, p<0.03, R2=-0.78, p<0.01 and R2=0.96, p<0.01, respectively. The bare soil, urban settlements and farm land increased by 38.9%, 8.4% and 10.7% respectively from the year 2000 to 2014 on the Tanzanian side. This could have led to water quality changes. Water quality parameters varied significantly between pelagic and littoral zones. Littoral zones are mostly polluted and thus should be the priority pollution control intervention areas.
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18

Zhou, Jian, Yuanyuan Wang, Fu Xiao, Yunyun Wang, and Lijuan Sun. "Water Quality Prediction Method Based on IGRA and LSTM." Water 10, no. 9 (August 27, 2018): 1148. http://dx.doi.org/10.3390/w10091148.

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Water quality prediction has great significance for water environment protection. A water quality prediction method based on the Improved Grey Relational Analysis (IGRA) algorithm and a Long-Short Term Memory (LSTM) neural network is proposed in this paper. Firstly, considering the multivariate correlation of water quality information, IGRA, in terms of similarity and proximity, is proposed to make feature selection for water quality information. Secondly, considering the time sequence of water quality information, the water quality prediction model based on LSTM, whose inputs are the features obtained by IGRA, is established. Finally, the proposed method is applied in two actual water quality datasets: Tai Lake and Victoria Bay. Experimental results demonstrate that the proposed method can take full advantage of the multivariate correlations and time sequence of water quality information to achieve better performance on water quality prediction compared with the single feature or non-sequential prediction methods.
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19

Haynes, David, Kerrie Lee, and Louisa Oswald. "Macroinvertebrate community structure and water quality variation in an effluent impacted wetlands (Lake Coleman), Victoria, Australia." Wetlands Australia 17, no. 1 (January 23, 2010): 1. http://dx.doi.org/10.31646/wa.182.

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20

Paterson, John. "Water Management and Recreational Values; Some Cases in Victoria, Australia." Water Science and Technology 21, no. 2 (February 1, 1989): 1–12. http://dx.doi.org/10.2166/wst.1989.0021.

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The growing recognition of recreational and amenity demands on water systems introduces a multitude of issues, many of them complex, to the established tasks of water quality management and water management generally. Victorian case studies are presented. They (1) illustrate the range and diversity of situations that can arise in managing competition and enhancing compatibility between traditional water supply objectives and recreational demands. (2) Fluctuation of storage levels, essential to storage operations, detract from recreational value. Recreational and tourism demands upon Lake Hume have grown to threaten traditional operating flexibility. (3) Mokoan is another such instance, but with its supply function in a state of flux, Lake Mokoan provides more scope for a shift in the balance. (4) Salinity management has become an issue in the management of lakes and wetlands when water supply interests and environmental/recreation interests respectively have different perspectives on salt disposal. (5) Recreational use of town supply sources has long been a vexed issue, although marked shifts in the attitudues of many supply authorities have occurred in recent years. (6) Eutrophication of lakes and estuaries raises difficult issues of responsibility and scientific uncertainty, and the water management connection may be tenuous but will attract public attention. (7) The water body attributes valued by specialised recreational interests require definition in terms that water managers can deal with using routine techniques of systems analysis and evaluation. (8) The demands of the fish population and anglers introduce a new perspective in river management and perceptions of instream values are changing markedly. (9) Direct costs of recreational services supplied by water authorities are not fully accounted: allocation choices and fiscal incidence will emerge as issues of significance. (10) These case studies raise only a fraction of the total range of matters that will, in the years to come, tax the technology and political skills of governments and management.
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21

Twesigye, Charles K. "The Impact of Land Use Activities on Vegetation Cover and Water Quality in the Lake Victoria Watershed." Open Environmental Engineering Journal 4, no. 1 (September 9, 2011): 66–77. http://dx.doi.org/10.2174/1874829501104010066.

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22

Vincent, Kiggundu, L. Mwebaza-Ndawula, B. Makanga, and Sarah Nachuha. "Variations in zooplankton community structure and water quality conditions in three habitat types in northern Lake Victoria." Lakes & Reservoirs: Research & Management 17, no. 2 (June 2012): 83–95. http://dx.doi.org/10.1111/j.1440-1770.2012.00504.x.

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23

Banadda, E. N., F. Kansiime, M. Kigobe, M. Kizza, and I. Nhapi. "Landuse-based nonpoint source pollution: a threat to water quality in Murchison Bay, Uganda." Water Policy 11, S1 (March 1, 2009): 94–105. http://dx.doi.org/10.2166/wp.2009.106.

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Murchison Bay in Lake Victoria is the main water source for Kampala City (Uganda) but is also the recipient for the wastewater discharged from the city. The objective of this paper is to trace the main landuse-based pollution sources within Kampala City borders and around Murchison Bay as a means to develop methods and systems to protect and preserve the aquatic environment and, from the lessons learned, to highlight what is considered to be an appropriate and sustainable approach for Uganda. This paper shows that Uganda needs to set realistic local standards, offer affordable services, set time frameworks, streamline politics, nurture and develop institutions, divide institutional responsibilities, educate her people and learn from the success stories to reverse the negative impacts on the water quality in Murchison Bay.
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24

Steve, Omari Ngodhe, Okoth Raburu Phillip, and Achieng Alfred. "The impact of water quality on species diversity and richness of macroinvertebrates in small water bodies in Lake Victoria Basin, Kenya." Journal of Ecology and The Natural Environment 6, no. 1 (January 31, 2014): 32–41. http://dx.doi.org/10.5897/jene2013.0403.

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25

Onyango, Dancan O., Christopher O. Ikporukpo, John O. Taiwo, and Stephen B. Opiyo. "Monitoring the extent and impacts of watershed urban development in the Lake Victoria Basin, Kenya, using a combination of population dynamics, remote sensing and GIS techniques." Environmental & Socio-economic Studies 9, no. 2 (June 1, 2021): 11–25. http://dx.doi.org/10.2478/environ-2021-0007.

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Abstract Several urban centres of different sizes have developed over time, and continue to grow, within the basin of Lake Victoria. Uncontrolled urban development, especially along the lake shore, puts environmental pressure on Lake Victoria and its local ecosystem. This study sought to monitor the extent and impacts of urban development (as measured by population growth and built-up land use/land cover) in the Lake Victoria basin, Kenya, between 1978 and 2018. Remote sensing and GIS-based land use/land cover classification was conducted to extract change in built-up areas from Landsat 3, 4, 5 and 8 satellite imagery obtained for the month of January at intervals of ten years. Change in population distribution and density was analysed based on decadal census data from the Kenya National Bureau of Statistics between 1979 and 2019. A statistical regression model was then estimated to relate population growth to built-up area expansion. Results indicate that the basin’s built-up area has expanded by 97% between 1978 and 2018 while the population increased by 140% between 1979 and 2019. Urban development was attributed to the rapidly increasing population in the area as seen in a positive statistical correlation (R2=0.5744) between increase in built-up area and population growth. The resulting environmental pressure on the local ecosystem has been documented mainly in terms of degradation of lake water quality, eutrophication and aquatic biodiversity loss. The study recommends the enactment and implementation of appropriate eco-sensitive local legislation and policies for sustainable urban and rural land use planning in the area. This should aim to control and regulate urban expansion especially in the immediate shoreline areas of the lake and associated riparian zones.
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26

Kanda, Edwin K., Job R. Kosgei, and Emmanuel C. Kipkorir. "Simulation of organic carbon loading using MIKE 11 model: a case of River Nzoia, Kenya." Water Practice and Technology 10, no. 2 (June 1, 2015): 298–304. http://dx.doi.org/10.2166/wpt.2015.035.

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River Nzoia is the largest river draining into the Kenyan portion of Lake Victoria. This river receives both point sources of pollution from industrial and municipal wastes, and non-point sources from agricultural runoff in the catchment. The objective of this study was to simulate dissolved oxygen (DO) and biochemical oxygen demand (BOD) of the middle section of River Nzoia using MIKE 11 model. The model was calibrated using discharge and water quality data for 2009 and validated with March–April 2013 data. The model performance was good with coefficient of determination (R2) values of between 0.845 and 0.995, Nash–Sutcliffe efficiency values of between 0.748 and 0.993 and percent bias of less than 10 for both calibration and validation of electrical conductivity (EC), DO and BOD. EC and BOD values were lower for April compared to March which could be attributed to dilution during high flows. DO values were above the recommended minimum level of 4 mg/l in all the sections of the river in the wet period but some sections had lower than 4 mg/l during low flow period. The government agencies such as Water Resources Management Authority and National Environment Management Authority should enforce the effluent standards to ensure that industries and wastewater treatment plants adhere to the maximum allowable limit for BOD and also improve their treatment efficiencies of wastewater plants so as to improve the quality of River Nzoia which is important in the overall management of the Lake Victoria basin.
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Meremo, Wankio Tabitha, Omondi Reuben, Yasindi Andrew Wamalwa, and Daniel Mungai Ndegwa. "Changes in water quality parameters and their effect on zooplankton distribution in a shallow bay of Lake Victoria, Kenya." International Journal of Fisheries and Aquatic Studies 10, no. 4 (July 1, 2022): 206–12. http://dx.doi.org/10.22271/fish.2022.v10.i4c.2714.

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28

Mulanda Aura, Christopher, Chrisphine S. Nyamweya, James M. Njiru, Reuben Omondi, Julius Manyala, Safina Musa, Horace Owiti, et al. "Using the Multi-metric Index of Biotic Integrity methodological approach to determine the major river catchment that most pollutes a lake." Aquatic Ecosystem Health & Management 24, no. 1 (January 2, 2021): 12–20. http://dx.doi.org/10.14321/aehm.024.01.04.

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Abstract We present the Multi-metric Index of Biotic Integrity methodological approach that allows for the ranking of major river catchments based on pollution status in the Kenyan portion of Lake Victoria, Africa. The study has a broader applicability to all of Lake Victoria, other African Great Lakes, and all lakes that have riverine discharge. The method presented utilizes water quality and environmental data, local knowledge, and pre-existing literature. The parameters considered were sampled from 2016 to 2018 during the dry season (July sampling) and the wet season (March sampling). Separation power of Mann-Whitney U test (p &lt; 0.05) qualified 11 discriminant metrics for both macroinvertebrate and fish samples into the scoring system of 1, 3 and 5 in the formulation of final Multi-metric Index of Biotic Integrity methodological approach. Rivers in the northern section had lower Multi-metric Index of Biotic Integrity methodological approach scores, as compared to southern counterparts. The Multi-metric Index of Biotic Integrity methodological approach ranking herein was validated by community perceptions on pollution levels. River Nzoia catchment emerged as the most polluted, followed by River Yala, River Kuja, and Sondu-Miriu. Siltation, domestic washing, litter and refuse emerged as the main agents of pollution. Management authorities ought to reinforce a balanced utilization of the vital water resources to minimize future impacts, and promote catchment wide practices that ensure ecological health sustainability of the lake ecosystem.
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Gichuki, John, Reuben Omondi, Priscillar Boera, Tom Okorut, Ally Said Matano, Tsuma Jembe, and Ayub Ofulla. "Water HyacinthEichhornia crassipes(Mart.) Solms-Laubach Dynamics and Succession in the Nyanza Gulf of Lake Victoria (East Africa): Implications for Water Quality and Biodiversity Conservation." Scientific World Journal 2012 (2012): 1–10. http://dx.doi.org/10.1100/2012/106429.

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This study, conducted in Nyanza Gulf of Lake Victoria, assessed ecological succession and dynamic status of water hyacinth. Results show that water hyacinth is the genesis of macrophyte succession. On establishment, water hyacinth mats are first invaded by native emergent macrophytes,Ipomoea aquaticaForsk., andEnydra fluctuansLour., during early stages of succession. This is followed by hippo grassVossia cuspidata(Roxb.) Griff. in mid- and late stages whose population peaks during climax stages of succession with concomitant decrease in water hyacinth biomass. Hippo grass depends on water hyacinth for buoyancy, anchorage, and nutrients. The study concludes that macrophyte succession alters aquatic biodiversity and that, since water hyacinth infestation and attendant succession are a symptom of broader watershed management and pollution problems, aquatic macrophyte control should include reduction of nutrient loads and implementing multifaceted approach that incorporates biological agents, mechanical/manual control with utilization of harvested weed for cottage industry by local communities.
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30

Ngodhe, Steve O., Phillip O. Raburu, Geraldine M. Kasisi, and Patrick O. Orwa. "Assessment of water quality, macroinvertebrate biomass and primary productivity of small water bodies for increased fish production in the Lake Victoria basin, Kenya." Lakes & Reservoirs: Research & Management 18, no. 2 (June 2013): 89–97. http://dx.doi.org/10.1111/lre.12029.

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31

Wanink, Jan, Frans Witte, and Mary Kishe-Machumu. "Dietary shift in benthivorous cichlids after the ecological changes in Lake Victoria." Animal Biology 58, no. 4 (2008): 401–17. http://dx.doi.org/10.1163/157075608x383700.

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AbstractCichlid fishes of Lake Victoria are well known for their trophic specializations. In our study area, the sub-littoral waters of the Mwanza Gulf (Tanzania), at least 12 trophic groups coexisted in the 1970s. After the Nile perch upsurge and eutrophication in the 1980s, most cichlids disappeared from the area. During the 1990s, heavy exploitation of Nile perch reduced the abundance of this predator. Subsequently, some cichlid species, mainly zooplanktivores and small benthivores, recovered. To establish their ecological role in the changed environment, among other factors we studied their diet. Stomach contents of fish caught before and after the ecological changes were compared. The small benthivores shifted from a diet dominated by detritus and phytoplankton, supplemented with small quantities of midge larvae and zooplankton, to a diet of invertebrate preys of larger sizes. Currently, the diet includes zooplankton, midge larvae, shrimps and molluscs, and a very small amount of detritus and phytoplankton. Apparently, the recovering benthivores have a more carnivorous than a herbivorous diet. Concomitantly, the ratio of intestine length to standard length of the benthivores decreased with 30% and the average stomach fullness decreased as well. The observed dietary shifts may be due to (1) the changed availability of food types and a decline of the nutritious quality of detritus and phytoplankton due to the strong increase of cyanobacteria in the lake, (2) the decline of the former trophic specialists, and (3) the reduced water clarity. The diet of the former detritivores is currently very similar to that of the zooplanktivores. Consequently, if diet plays a role in the relatively slow recovery of the small benthivores compared to the zooplanktivores, this would only hold if they are relatively poorly adapted to their new diet.
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32

I. Z., Mukasa-Tebandeke, Karume I., Wasajja H. Z., and Nankinga R. "Improving Quality of Water from Murchison bay Using Clay from Chelel, Kapchorwa District, Uganda." Academic Journal of Chemistry, no. 411 (November 10, 2019): 102–17. http://dx.doi.org/10.32861/ajc.411.102.117.

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Pollution resulting from increased human activities is threatening Lake Victoria, its effects are characterized by eutrophication, high turbidity, pH, iron(II) concentration and chemical oxygen demand (COD). In this study we have investigated the effect of Fe-montmorillonite clay from Chelel on turbidity, pH, concentration of iron, total suspended soils, total nutrients and COD of water sampled from Murchison bay watershed of Nakivubo channel south of Kampala. Varying amounts of clay powder was vigorously stirred with water samples for 5 minutes, filtered using Whatman paper at ambient temperatures. The optimum concentration of clay of 0.4 gL-1 was found to produce 73.5+2% fall in COD indicating elimination of microbes and organic waste. The pH of water became 6.3+ 0.2 showing that impurities had been bound to clay. The TSS and nutrients in MB water also decreased greatly when clay was stirred with water at ambient temperatures. The available data can be relied on to recommend use of this clay in treatment of waste water and/or sewage from Kampala. Further studies on combined use of clays with alums, zeolites and/or lime need to be carried out.
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Guinaldo, Thibault, Simon Munier, Patrick Le Moigne, Aaron Boone, Bertrand Decharme, Margarita Choulga, and Delphine J. Leroux. "Parametrization of a lake water dynamics model MLake in the ISBA-CTRIP land surface system (SURFEX v8.1)." Geoscientific Model Development 14, no. 3 (March 10, 2021): 1309–44. http://dx.doi.org/10.5194/gmd-14-1309-2021.

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Abstract. Lakes are of fundamental importance in the Earth system as they support essential environmental and economic services, such as freshwater supply. Streamflow variability and temporal evolution are impacted by the presence of lakes in the river network; therefore, any change in the lake state can induce a modification of the regional hydrological regime. Despite the importance of the impact of lakes on hydrological fluxes and the water balance, a representation of the mass budget is generally not included in climate models and global-scale hydrological modeling platforms. The goal of this study is to introduce a new lake mass module, MLake (Mass-Lake model), into the river-routing model CTRIP to resolve the specific mass balance of open-water bodies. Based on the inherent CTRIP parameters, the development of the non-calibrated MLake model was introduced to examine the influence of such hydrological buffer areas on global-scale river-routing performance. In the current study, an offline evaluation was performed for four river networks using a set of state-of-the-art quality atmospheric forcings and a combination of in situ and satellite measurements for river discharge and lake level observations. The results reveal a general improvement in CTRIP-simulated discharge and its variability, while also generating realistic lake level variations. MLake produces more realistic streamflows both in terms of daily and seasonal correlation. Excluding the specific case of Lake Victoria having low performances, the mean skill score of Kling–Gupta efficiency (KGE) is 0.41 while the normalized information contribution (NIC) shows a mean improvement of 0.56 (ranging from 0.15 to 0.94). Streamflow results are spatially scale-dependent, with better scores associated with larger lakes and increased sensitivity to the width of the lake outlet. Regarding lake level variations, results indicate a good agreement between observations and simulations with a mean correlation of 0.56 (ranging from 0.07 to 0.92) which is linked to the capability of the model to retrieve seasonal variations. Discrepancies in the results are mainly explained by the anthropization of the selected lakes, which introduces high-frequency variations in both streamflows and lake levels that degraded the scores. Anthropization effects are prevalent in most of the lakes studied, but they are predominant for Lake Victoria and are the main cause for relatively low statistical scores for the Nile River However, results on the Angara and the Neva rivers also depend on the inherent gap of ISBA-CTRIP process representation, which relies on further development such as the partitioned energy budget between the snow and the canopy over a boreal zone. The study is a first step towards a global coupled land system that will help to qualitatively assess the evolution of future global water resources, leading to improvements in flood risk and drought forecasting.
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Kiggundu, Nicholas, Listowel Abugri Anaba, Noble Banadda, Joshua Wanyama, and Isa Kabenge. "Assessing Land Use and Land Cover Changes in the Murchison Bay Catchment of Lake Victoria Basin in Uganda." Journal of Sustainable Development 11, no. 1 (January 30, 2018): 44. http://dx.doi.org/10.5539/jsd.v11n1p44.

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The Murchison Bay catchment in the northern shoreline of Lake Victoria basin is a high valued ecosystem because of the numerous human-related activities it supports in Uganda. The catchment has undergone tremendous human-induced land use/cover changes, which have not been quantified. This study aimed at quantifying the land use/cover changes as well as the rate at which these changes occurred over the last three decades in the catchment. This was achieved using remote sensing techniques and Geographic Information System (GIS) to analyse and contextualize the changes. To that effect, images of Landsat satellites MSS, TM, ETM+ and OLI were interpreted using supervised image classification technique to determine the land use/land cover changes from 1984 to 2015. The obtained results indicated that the catchment has undergone huge land use and land cover transformations over the last three decades attributable to rapid population growth and urbanization. The prevailing changes in footprint between 1984 and 2015 were expansions of built–up land (20.58% to 49.59%) and open water bodies (not detected in 1984 to 1.74%), and decreases in the following sectors: agricultural lands (from 43.88% to 26.10%), forestland (from 23.78% to 17.49%), and wetlands (from 11.76% to 5.08%). The changes pose a threat to the environment and water quality of the Murchison Bay and consequently increases National Water and Sewerage Corporation water treatment costs. Therefore, there is the need to take critical and practical measures to regulate and police land use, water use rights and conserve the environment especially wetlands.
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35

Otieno, EO, and TK Olielo. "Effects of socio-economic conditions of small-scale traders on quality of post harvest tilapia in Kisumu." African Journal of Food, Agriculture, Nutrition and Development 14, no. 61 (March 12, 2014): 8545–58. http://dx.doi.org/10.18697/ajfand.61.12805.

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The small - scale fisheries and fish trade sector is important in global and national economies by providing millions with income and consumers with food. Nile perch (Lates niloticus ), Nile tilapia ( Oreochromis niloticus ), and small cyprinid ( Rastrineobola argentea ) form the basis of commercial fishery in Lake Victoria. From 1997 to 2000, East Africa suffered a series of fish export bans due to contamination by Salmonella, cholera epidemics and use of chemicals in Lake Victoria. Kenya thereafter adopted hygiene requirements in European directive 91/493/EEC for fish and fish products. Kenya’s fish production from the lake declined from 180,000 metric tons in 2003 , down to 133,000 metric tons in 2010. Globally, 30% of total fish catch is lost through poor post harvest handling. The objectives of this study were to determine the socio - economic conditions of small - scale fish traders, to investigate hygienic practices in handling, storage and processing of fish, and to isolate and identify human pathogens in both fresh and processed fish sold in Kisumu markets. A structured questionnaire was used to get demographic, socio - economic, safety and quality practices information. Samples of fresh and processed fish were tested for Aerobic Plate Count, Coliform, Escherichia coli and Vibrio cholerae counts. Results revealed that women traders were 81% in number while men were 19% and most of the traders (40%) were aged between 26 and 35 years. The highest level of education attained by majority (51%) of the traders was primary level. The traders’ most frequent income was KES 200 - 399 (USD 3 to 5) a day which cannot sustain a family. Most traders (57%) had additional sources of income to subsidise their needs. Many traders lacked good transport, refrigeration facilities, water, toilet, waste disposal and rubbish disposal. Total plate count was above 10 6 per g which is the maximum allowed. Th e association between Total Plate Count and hygiene quality status of the samples was significant negatively at p value ≤ 0.001. Traders should be trained on hygiene requirements and economic skills for better practices to improve business performance.
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36

Simonit, Silvio, and Charles Perrings. "Indirect economic indicators in bio-economic fishery models: agricultural price indicators and fish stocks in Lake Victoria." ICES Journal of Marine Science 62, no. 3 (January 1, 2005): 483–92. http://dx.doi.org/10.1016/j.icesjms.2005.01.012.

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Abstract We consider the potential for using prices as leading indicators of changes in stocks and yields in the freshwater capture fishery in Lake Victoria. Fertilizer run-off from agricultural land is a major cause of nutrient loading, along with soil erosion, atmospheric deposition, and point pollution from industrial and domestic affluent. The interactions between fertilizer applications, water quality, fish stocks, and yields are modelled in order to predict the effect of changes in the price of fertilizers on the fishery. The fishery model includes a measure of Chl a concentration (a proxy for phytoplankton density). The consequences of changes in Chl a concentration for fish stocks are modelled using Ecopath. We show that fertilizer prices are effective leading indicators of changes in fish biomass and yield.
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37

Kanda, Edwin K., Emmanuel C. Kipkorir, and Job R. Kosgei. "Modelling of nitrates in River Nzoia using MIKE 11." Water Practice and Technology 12, no. 1 (March 1, 2017): 217–23. http://dx.doi.org/10.2166/wpt.2017.026.

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Eutrophication is a serious problem in Lake Victoria as a result of enrichment by nutrients transported by the rivers draining into it. River Nzoia is one of the main rivers draining into the lake. The main aim of this study was to simulate the level of nitrates using MIKE 11 and to establish relationship between nitrogen and phosphorus. The model was calibrated using water quality data for 2009 and validated with March 2013 data and then it was used to simulate nitrate concentration for the wet month of April 2013. The model performance was good with R2 values of between 0.87 and 0.98 and EF values of between 0.73 and 0.96. From the simulations, the effluent discharge from municipal and industrial wastewater ponds elevated the concentration of the nitrates in the river. Analysis of the concentrations of nitrates for wet and dry periods showed significant variations indicating significant contributions from the catchment through run-off. The relationship between total nitrogen and total phosphorus was analysed and found to have a strong positive correlation (r = 0.714, p &lt; 0.05) indicating that both originate from similar sources or are influenced by the same factors such as agriculture.
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38

I. Z, Mukasa-Tebandeke, Karume I, Wasajja H. Z, and Nankinga R. "Improving Quality of Water from Murchison Bay using Clay from Chelel, Kapchorwa District, Ugandao." JOURNAL OF ADVANCES IN CHEMISTRY 17 (January 4, 2020): 1–29. http://dx.doi.org/10.24297/jac.v17i.8537.

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Pollution resulting from increased human activities is threatening Lake Victoria, its effects are characterized by eutrophication, high turbidity, pH, iron(II) concentration and chemical oxygen demand (COD). In this study we have investigated the effect of Fe-montmorillonite clay from Chelel on turbidity, pH, concentration of iron, total suspended soils, total nutrients and COD of water sampled from Murchison bay watershed of Nakivubo channel south of Kampala. Varying amounts of clay powder was vigorously stirred with water samples for 5 minutes, filtered using Whitman paper at ambient temperatures. The optimum concentration of clay of 0.4gl-1 was found to produce 73.5+ 2% fall in COD indicating elimination of microbes and organic waste. The pH of water became 6.3+ 0.2 showing that impurities had been bound to clay. The turbidity of filtrate dropped to 15.7+ 0.3NTUshowing that clarity of water was improved by adsorption of suspended solids to clay minerals. The concentration of iron(II) fell from 3.7 + 0.3 to 2.5+ 0.2mgl-1 indicating fairly high extent of heavy metal removal from Murchison bay (MB) waters. The TSS and nutrients in MB water also decreased greatly when clay was stirred with water at ambient temperatures. The available data can be relied on to recommend use of this clay in treatment of waste water and/or sewage from Kampala. Further studies on combined use of clays with alums, zeolites and/or lime need to be carried out.
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39

Worthington, E. Barton, and Rosemary Lowe-McConnell. "African Lakes Reviewed: Creation and Destruction of Biodiversity." Environmental Conservation 21, no. 3 (1994): 199–213. http://dx.doi.org/10.1017/s0376892900033166.

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The lakes of Africa provide outstanding examples of biodiversity. Some hundreds of species of aquatic fauna, especially fishes, have been created through evolution taking place in environments which became isolated from each other. The lakes also provide an outstanding example of the loss of biodiversity: in Lake Victoria at least 200 species of fish have almost certainly become extinct through human activities. These lakes have, since Mankind's origin in Africa, provided high-quality animal protein food and with improved management they could provide much more, which adds greatly to their scientific and economic interest.
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40

Mchau, Geofrey J., Edna Makule, Revocatus Machunda, Yun Yun Gong, and Martin Kimanya. "Phycocyanin as a proxy for algal blooms in surface waters: case study of Ukerewe Island, Tanzania." Water Practice and Technology 14, no. 1 (January 8, 2019): 229–39. http://dx.doi.org/10.2166/wpt.2019.005.

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Abstract Knowledge of the parameters that contribute to water body eutrophication is essential for proper monitoring and management of water quality for human consumption. This study assessed water quality parameters in relation to phycocyanin (PC) as a proxy indicator for harmful algal blooms (HABs). Samples were collected from 23 water sources – lakes, wells, springs and boreholes – in selected villages, for six months. Parameters measured included temperature, pH, redox potential, dissolved oxygen, electrical conductivity, total dissolved solids, nitrate nitrogen, nitrite nitrogen, phosphorus, reactive phosphate and total chlorophyll, which were related to (PC) occurrence. The PC concentration detected in Lake Victoria ranged from 5 to 58.4 μg/l above the WHO alert level and exceeded that in other water sources by almost 30 μg/l (P &lt; 0.001). Univariate relationship between water quality parameters and PC indicates association with temperature, redox potential, total chlorophyll, nitrate nitrogen, nitrite nitrogen, phosphate and reactive phosphorus (P &lt; 0.001). The multivariate model indicates that redox potential, nitrate nitrogen and phosphorus are significant statistically (P &lt; 0.05). A predictive model indicates that nitrate nitrogen and reactive phosphorus contribute significantly to PC occurrence whereby unit (1 mg/l) increases in these parameters increase PC by 9.55 and 4.38 μg/l (P &lt; 0.05) respectively. This study demonstrates that water quality parameters can be used to predict increases in PC and hence as a proxy for HABs. It remains important to be able to classify algal blooms, to understand which species are present and their potential cyanotoxin production.
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41

Pollino, Carmel A., Pat Feehan, Michael R. Grace, and Barry T. Hart. "Fish communities and habitat changes in the highly modified Goulburn Catchment, Victoria, Australia." Marine and Freshwater Research 55, no. 8 (2004): 769. http://dx.doi.org/10.1071/mf03180.

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Evidence for the decline in native fish communities in the lowland Goulburn Catchment has been based primarily on studies investigating changes to environmental conditions as a result of river regulation. The present study aggregates historical fisheries data to spatially compare native fish communities in different parts of the catchment. Multivariate analyses demonstrate that distinctly different community compositions are found in different parts of the catchment. Eildon Dam, a deep release reservoir, has drastically altered the hydrology and water quality of the upper Goulburn River, and ordination analyses show that this has created both physical and artificial barriers to movement of native fish into the main channel. Concurrently, fisheries data from the upper main channel show the community is highly divergent compared to the remaining catchment. Further downstream, Goulburn Weir creates a barrier to fish movement between Lake Nagambie and the lower Goulburn Catchment, and alters the natural hydrological regime. Similarity Percentage analyses demonstrate that these stressors have facilitated the establishment of alien species, which dominate fish abundance in the upper and lower main channels. The current study emphasises the need to explore alternatives for improving management strategies to rehabilitate fish communities throughout the Goulburn Catchment.
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42

Syariz, Muhammad Aldila, Chao-Hung Lin, Dewinta Heriza, Umboro Lasminto, Bangun Muljo Sukojo, and Lalu Muhamad Jaelani. "A Transfer Learning Technique for Inland Chlorophyll-a Concentration Estimation Using Sentinel-3 Imagery." Applied Sciences 12, no. 1 (December 25, 2021): 203. http://dx.doi.org/10.3390/app12010203.

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Chlorophyll-a (Chla) concentration, which serves as a phytoplankton substitute in inland waters, is one of the leading indicators for water quality. Generally, water samples are analyzed in professional laboratories, and Chla concentrations are measured regularly for the purpose of water quality monitoring. However, limited spatial water sampling and the labor-intensive nature of data collection make global and long-term monitoring difficult. The developments of remote-sensing optical sensors and technologies make the long-term monitoring of Chla concentrations for an entire water body more achievable. Many studies based on machine learning techniques, such as regression and artificial neural network (ANN) methods, have recently been proposed for Chla concentration estimation using optical satellite images. The methods based on machine learning can achieve accurate estimation. However, overfitting problems may arise because the in situ Chla dataset is generally insufficient to train a complicated machine learning model, which makes trained models inapplicable. In this study, an ANN model containing three convolutional and two fully connected layers with 4953 unknown parameters is designed. A transfer learning method, consisting of model pretraining, main-training, and fine-tuning stages, is proposed to ease the problem of insufficient in situ samples. In the model pretraining stage, the ANN model is pretrained and initialized using samples derived from an existing Chla concentration model. The pretrained ANN model is then fine-tuned using the proposed transfer learning technique with in situ samples collected in five different campaigns carried out during early 2019 from Laguna Lake, the Philippines. Before the transfer learning, data augmentation and rebalancing methods are conducted to enrich the variability and to near-uniformly distribute the in situ samples in Chla concentration space, respectively. To estimate the alleviation of model overfitting, the trained ANN model, using an in situ dataset from Laguna Lake, was tested using an in situ dataset from Lake Victoria, Uganda, obtained in 2019, which has a similar trophic state as Laguna Lake. The experimental results from Sentinel-3 imagery indicated that the overfitting problem was significantly alleviated and the trained ANN model outperformed related models in terms of the root-mean-squared error of the estimated Chla concentrations.
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43

Monbet, Phil, Ian D. McKelvie, and Paul J. Worsfold. "Phosphorus speciation, burial and regeneration in coastal lagoon sediments of the Gippsland Lakes (Victoria, Australia)." Environmental Chemistry 4, no. 5 (2007): 334. http://dx.doi.org/10.1071/en07049.

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Environmental context. Eutrophication can lead to the production of harmful algal blooms and is one of the world’s most serious water quality issues. Phosphorus is potentially the limiting macro-nutrient in fresh, estuarine and some marine waters. Consequently, it plays a crucial role in determining the ecological status of many aquatic ecosystems. Considerable effort has been invested in monitoring dissolved reactive phosphorus and total phosphorus in the water column, but less is known about the speciation of phosphorus, particularly in the sediment. This compartment is an important and dynamic reservoir of phosphorus and a potential long-term source of phosphorus release to the water column by the sediment–water interface. This paper investigates the solid-phase speciation and reorganisation of phosphorus within the sediments of a shallow lake system in south-east Australia (the Gippsland Lakes) which suffers from recurring harmful algae blooms. Various strategies are proposed to determine the minimum realistic timescale required to deplete the sediment of labile and reactive phosphorus species. Abstract. Solid-phase phosphorus pools in the sediments of two shallow lakes (Wellington and Victoria) in the Gippsland Lakes coastal lagoon system of south-east Australia are discussed. Cores (20-cm depth) were taken in summer and winter in both lakes and a sequential extraction scheme (SEDEX) was used to profile the exchangeable P (Pex), iron oxide/hydroxide bound P (PFe), authigenic P (Pauth), detrital P (Pdet) and organic P (Porg). Pore-water (Ppw) dissolved reactive phosphorus concentration profiles were also measured. The dominant forms of P were PFe (up to 53%) and Porg (35–55%), with the PFe fraction playing a key role in the short-term retention of P in the sediment. Benthic phosphorus fluxes at the sediment–water interface (μmol m–2 d–1) were determined from the sequential extraction data. The results were compared with flux measurements from the complementary approaches of benthic chamber experiments and Fickian diffusion calculations, to allow an insight into the nature and seasonal variations of the fluxes. The burial flux of phosphorus was also estimated from excess 210Pb profiles in the sediment of the lakes. All of these data were used to produce a phosphorus budget for the Gippsland Lakes which suggested that the sediment represents a substantial source of phosphorus within the lakes and thus clearly highlights the importance of the sedimentary compartment in shallow eutrophic ecosystems. Minimum realistic timescales for complete labile phosphorus depletion from the sediment (assuming no resupply from the sediment–water interface) were calculated and ranged from 8 to 22 years.
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44

Massawe, Ezrael J., and Richard Kimwaga. "Modelling Transport of Heavy Metals in Geita Wetland along Mamubi River." Tanzania Journal of Engineering and Technology 37, no. 1 (December 31, 2018): 72–88. http://dx.doi.org/10.52339/tjet.v37i1.484.

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The modelling of heavy metals in rivers is highly dependent on hydrodynamics, the transport of suspended particulate matter and the partition between dissolved and particulate phases. This paper presents the development of hydrodynamic model DUFLOW, which is a one dimensional flow and water quality simulation package, that describes the processes governing transformations and transport of heavy metals (Hg, Ni and Cu) along Mabubi River in the Geita wetland. Two monitoring stations were established along Mabubi River at the inlet (MBSP1) and outlet (MBSP2) of the wetland. A set of DUFLOW model inputs representative of the water conditions were collected from the established monitoring stations. The model was calibrated and validated for the prediction of flow and heavy metals (Hg, Ni, and Cu) transport, against a set of measured mean monthly monitoring data. Sensitive model parameters were adjusted within their feasible ranges during calibration to minimize model prediction errors. At the gauging station MBSP2, the calibration results showed the model predicted mean monthly flow within 17% of the measured mean monthly flow while the r2 coefficient and Nash-Sutcliffe (NSE) were 0.83 and 0.79 respectively. At the water quality monitoring station MBSP2, the calibration results showed the model predicted heavy metals (Hg, Ni and Cu) concentrations within 13% and 17% of their respective measured mean monthly concentrations. The mean monthly comparisons r 2 values for heavy metals ranged from 0.75 to 0.88 while the NSE values were between 0.70 and 0.82. The model results and field measurements demonstrated that about 40% of the annual heavy metals loadings which would otherwise reach the Lake Victoria are retained in the wetland. The Mabubi river model can therefore be used for prediction of heavy metals (Hg. Ni and Cu) transformation processes in the Geita wetland.
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Musa, Safina M., Christopher Mulanda Aura, Charles Chege Ngugi, and Rodrick Kundu. "The Effect of Three Different Feed Types on Growth Performance and Survival of African Catfish Fry (Clarias gariepinus) Reared in a Hatchery." ISRN Zoology 2012 (July 31, 2012): 1–6. http://dx.doi.org/10.5402/2012/861364.

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African catfish Clarias gariepinus is cultured as food fish, used to control overpopulation in tilapia ponds, and is grown as baitfish for the Lake Victoria Nile Perch fishery. Since the demand for Clarias gariepinus fingerlings is high, many farmers wish to specialize in fingerling production. In this study, the performance of three dietary feed types: freshwater rotifers with Artemia nauplii, freshwater rotifers with fish meal, and freshwater rotifers with maize bran, on the growth performance of African catfish fry, were done in a hatchery and they were raised in 9 glass tanks for a period of 21 days. Pearson’s correlation showed no relationship (r=0.1; P>0.05) between growth and water quality parameters, but indicated a strong relationship between survival rate and total length between treatments (r=0.85; P=0.02). Mean total length (TL) after 21 days were (A=15.003), (B=12.964), and (C=11.90) in mm for Treatments A, B, and C, respectively. Treatment A had the highest specific growth rate (SGR) of 6.475% day 1 followed by B (5.5320% day−1) and C (4.960% day−1). Results from this study demonstrate that after the 7 days of feeding using rotifers, Artemia is the best feed for increasing growth of Clarias gariepinus.
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46

Turyahabwe, Nelson, David Mwesigye Tumusiime, Willy Kakuru, and Bernard Barasa. "Wetland Use/Cover Changes and Local Perceptions in Uganda." Sustainable Agriculture Research 2, no. 4 (September 1, 2013): 95. http://dx.doi.org/10.5539/sar.v2n4p95.

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<p>With increasing population, coupled with land shortage and weather variations, wetlands in Uganda have continued to face degradation due to mainly conversion for agricultural, industrial and settlement purposes. The objective of this study was to determine the spatial and temporal wetland use/cover changes and local perceptions attributed to these changes. The study utilized three sets of ortho-rectified and cloud free Landsat TM/ETM+/MSS temporal images (30 m) of 1986, 2000 and 2011. The classification procedures were carried out using an Integrated Land and Water Information System (ILWIS) software version 3.7. A wetland classification system for Uganda developed by the National Biomass Study, 2003 was adopted to describe the wetland use/cover types. The classified images were validated in a ground truthing exercise using Global Positioning System (GPS) to improve on the classification accuracy. Key informant interviews and focus group discussions were conducted with communities adjacent to the wetlands in each of three of the ten Ugandan agro-ecological zones to determine the underlying drivers of wetland use/cover changes, while household interviews generated information on local perceptions of the changes. Significant changes were mainly observed in wetland use/cover between 1986 and 2011. Major factors responsible for these changes were subsistence farming due to intensification of growing paddy rice in Kyoga plains, an influx of migrants who accessed wetlands for daily subsistence (livestock grazing) in South western farmlands and proximity to urban centres in the Lake Victoria Crescent. In all the sampled agro-ecological zones, increased crop farming in wetlands was due to changing opportunities created by existent large markets for wetland crops. Majority (60%) of the local people perceived wetlands in their proximity to have undergone high degradation within the last 10 years, and to have declined in quantity and quality of vegetation, soil fertility and water levels. There was a noticeable variation across the sampled agro-ecological zones, with the highest proportion of local communities perceiving degradation being in Kyoga plains (76%), followed by Lake Victoria crescent (63%) and South-western farmlands (41%). Locally perceived threats to wetlands were mainly from crop growing that accounted for 33% of the frequency of mentioned threats, collection of wetland resources (30%), and prolonged floods and droughts (12%). This study confirms the importance of economic opportunities from new market outlets and migration in its various forms as key factors in land use change, especially at timescales of a couple of decades.<strong></strong></p>
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Onyutha, Charles, Agnieszka Rutkowska, Paul Nyeko-Ogiramoi, and Patrick Willems. "How well do climate models reproduce variability in observed rainfall? A case study of the Lake Victoria basin considering CMIP3, CMIP5 and CORDEX simulations." Stochastic Environmental Research and Risk Assessment 33, no. 3 (September 14, 2018): 687–707. http://dx.doi.org/10.1007/s00477-018-1611-4.

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48

Berg, Håkan, Deogratias Mulokozi, and Lars Udikas. "A GIS Assessment of the Suitability of Tilapia and Clarias Pond Farming in Tanzania." ISPRS International Journal of Geo-Information 10, no. 5 (May 20, 2021): 354. http://dx.doi.org/10.3390/ijgi10050354.

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Aquaculture production in Tanzania has increased in recent years, responding to an increased demand for fish, but the scale and productivity of smallholder aquaculture remains below the level needed to support significant sector growth in Tanzania. This study assesses, through geospatial analyses, the suitability for freshwater pond farming of Oreochromis niloticus and Clarias gariepinus in Tanzania, by assessing the geographical distribution of seven criteria (water availability, water temperature, soil texture, terrain slope, availability of farm inputs, potential farm-gate sales, and access to local markets) identified as important for fish pond farming. The criteria were developed and standardized from 15 sub-criteria, which were classified into a four-level suitability scale based on physical scores. The individual weights of the different criteria in the overall GIS suitability assessment were determined through a multi-criteria evaluation. The final results were validated and compared through field observations, interviews with 89 rural and 11 urban aquaculture farmers, and a questionnaire survey with 16 regional fisheries officers. Our results indicate that there is a good potential for aquaculture in Tanzania. Almost 60% of Tanzania is assessed as being suitable and 40% as moderately suitable for small-scale subsistence pond farming, which is the dominating fish farming practice currently. The corresponding figures for medium-scale commercial farming, which many regions expect to be the dominating farming method within ten-years, were 52% and 47% respectively. The availability of water was the most limiting factor for fish pond farming, which was confirmed by both farmers and regional fisheries officers, and assessed as being “suitable” in only 28% of the country. The availability of farm-gate sales and local markets were “moderate suitable” to “suitable” and were seen as a constraint for commercial farms in rural areas. The availability of farm inputs (agriculture waste and manure) was overall good (26% very suitable and 32% suitable), but high-quality fish feed was seen as a constraint to aquaculture development, both by farmers and regional fisheries officers. Soil, terrain, and water temperature conditions were assessed as good, especially at low altitudes and in regions close to the sea and south of Lake Victoria.
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Massawe, Ezrael J., Richard Kimwaga, and Fredrick Mwanuzi. "Modelling Transport of Nitrogen Compounds in Geita Wetland along Mtakuja River." Tanzania Journal of Engineering and Technology 37, no. 2 (June 30, 2018): 89–106. http://dx.doi.org/10.52339/tjet.v37i2.486.

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The impacts of excessive nitrogen loading to streams in a watershed occur in the receiving waters such as rivers at the outlet of the watershed. To quantify the impacts of land use and management practices on the nitrogen loading at the watershed outlet, simulation models are needed that can both predict the nitrogen loading at the edge of individual fields and predict the fate of nitrogen as it moves through the river network to the watershed outlet. This paper presents the results of a model analysis for describing the processes governing transformations and transport of nitrogen compounds (NO3-N and NH4-N) through Mtakuja River in the Geita wetland. The model was made in Soil and Water Assessment Tool (SWAT), a watershed model developed to assess the impact of land management practices on water, sediment and agricultural chemical yields with varying soils, land use and management conditions. Two monitoring stations namely MTSP1 and MTSP2 were established along Mtakuja River. A set of SWAT model inputs representative of the water conditions was collected from the established monitoring stations. The model was calibrated and validated for the prediction of flow and nitrogen compounds (NO3-N and NH4-N) transport, against a set of measured mean monthly monitoring data. Sensitive model parameters were adjusted within their feasible ranges during calibration to minimize model prediction errors. At the gauging station MTSP2, the calibration results showed that the model predicted mean monthly flow within 18% of the measured mean monthly flow with the r2 coefficient and Nash-Sutcliffe (NSE) were 0.84 and 0.82, respectively. At the water quality monitoring station MTSP2, the calibration results showed the model predicted nitrogen compounds (NO3-N and NH4-N) loadings within 21% and 23% of their respective measured mean monthly loadings. The mean monthly comparisons of r 2 values for nitrogen compounds ranged from 0.77 to 0.81 while the Nash-Sutcliffe Efficiency (NSE) values were between 0.72 and 0.73. The model results and field measurements demonstrated that about 70% of the annual nitrogen compounds loadings which would otherwise reach Lake Victoria are retained in the wetland. The Mtakuja river model can therefore be used for prediction of nitrogen compounds (NO3-N and NH4-N) transformation processes in the Geita wetland.
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van Griensven, A., P. Ndomba, S. Yalew, and F. Kilonzo. "Critical review of SWAT applications in the upper Nile basin countries." Hydrology and Earth System Sciences 16, no. 9 (September 20, 2012): 3371–81. http://dx.doi.org/10.5194/hess-16-3371-2012.

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Abstract. The Soil and Water Assessment Tool (SWAT) is an integrated river basin model that is widely applied within the Nile basin. Up to date, more than 20 peer-reviewed papers describe the use of SWAT for a variety of problems in the upper Nile basin countries, such as erosion modelling, land use and climate change impact modelling and water resources management. The majority of the studies are focused on locations in the tropical highlands in Ethiopia and around Lake Victoria. The popularity of SWAT is attributed to the fact that the tool is freely available and that it is readily applicable through the development of geographic information system (GIS) based interfaces and its easy linkage to sensitivity, calibration and uncertainty analysis tools. The online and free availability of basic GIS data that are required for SWAT made its applicability more straightforward even in data-scarce areas. However, the easy use of SWAT may not always lead to appropriate models which is also a consequence of the quality of the available free databases in these regions. In this paper, we aim at critically reviewing the use of SWAT in the context of the modelling purpose and problem descriptions in the tropical highlands of the Nile basin countries. To evaluate the models that are described in journal papers, a number of criteria are used to evaluate the model set-up, model performances, physical representation of the model parameters, and the correctness of the hydrological model balance. On the basis of performance indicators, the majority of the SWAT models were classified as giving satisfactory to very good results. Nevertheless, the hydrological mass balances as reported in several papers contained losses that might not be justified. Several papers also reported the use of unrealistic parameter values. More worrying is that many papers lack this information. For this reason, most of the reported SWAT models have to be evaluated critically. An important gap is the lack of attention that is given to the vegetation and crop processes. None of the papers reported any adaptation to the crop parameters, or any crop-related output such as leaf area index, biomass or crop yields. A proper simulation of the land cover is important for obtaining correct runoff generation, evapotranspiration and erosion computations. It is also found that a comparison of SWAT applications on the same or similar case study but by different research teams and/or model versions resulted in very different results. It is therefore recommended to find better methods to evaluate the representativeness of the distributed processes and parameters (especially when land use studies are envisaged) or predictions of the future through environmental changes. The main recommendation is that more details on the model set-up, the parameters and outputs should be provided in the journal papers or supplementary materials in order to allow for a more stringent evaluation of these models.
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